🔭 LLM Observability

Best LLM observability tools in 2026 — our verdict

Once your AI app hits production, you need tracing, evals and cost monitoring — prompt-and-pray doesn't scale. Langfuse is the leading open-source option with a generous self-host path, LangSmith is the natural fit if you already build on LangChain, Helicone is the fastest way to add observability via a proxy, Braintrust excels at evals-driven development, and Arize Phoenix plus LangWatch round out strong open-source and EU-friendly choices.

Pricing here is usage-based and can surprise you: trace volume, retention windows and seat counts all move the bill. Start with a free tier on real production traffic, measure your trace volume, then compare. Our Langfuse vs LangSmith and LangSmith alternative guides break down the decision in detail.